Assigxob to the westees



(Model.) 2 Sheets-Sheet 1.

C. E. SCRIBNER. DUPLIGATE SWITCH BOARD SYSTEM FOR TELEPHONES.

Patented June so, 1885.

(Model.) Y 2 Sheets-Sheet 2.. C. E. SCRIBNER. DUPLIGATE SWITCH BOARD SYSTEM EUR TELEPHONES. No. 321.390. Patented June 30, 1885.l

iran Starts Partnr @tries3 CHARLES E. SCRIBNER, OF CHIC-AGO, ILLINOIS, ASSIGNCR V'TO THE TESTER-N ELECTRIC MANUFACTURING COMPANY.

DUPLICATE SWlTCH-BOARD SYSTEM FOR. TELPHGNES.

SPECIFICATION forming part of Letters Patent No. 321,390, dated June 30, 1835.

Application tiled Dttobcr 35, 1S9. Renewed May 23, 1885.

(Model.) Patented in England November Q9, 1879, No. 4.903; in France January 16, ISEO, No. llLSFl, nnd in Belgium January 28, 1550, No. 50,413.

.To all whom t may concern,.-

Be it known that I, CHiinLns E. SCRIBNER, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Multiple Switch-Board Systems, (Case 3,) of which the following is a full, clear, concise, and exact description,reference being had to the accompanying drawings,i`orni ing a part of' this specification.

A district telephone exchange consists of a central office with which the telephones ot' many subscribers are connected by independent lines, and where, upon request, any one subscriber may be putin communication with any other one of the subscribers. All the independent lines, therefore, must be connected with a single switch-board. Vhen the number of subscribers is large, and a single attendant cannot do the necessary switching, duplicate switch-boards are provided, all the wires being branched to each of the duplicate boards, so that each board is complete in itself, and thus any two subscribers may be connected by an attendant at any one of the duplicate boards. An additional board is required for about every two hundred and fifty new subscribers. The subscribers are apportioned, so that a switchman at a given board answers only the calls of those assigned to his board. Nhen a third subscriber wishes to communicate with one of two who are already connected, great confusion often arises. This is wholly or partially obviated, as the case may be, by the use of my invention, which consists in so placing the cut-outs or switches and connecting them from one board to the other that the switchmen, respectively, at the different boards may readily ascertain. whether the wire of a subscriber called for is in usethat is, whether it is connected with the wire of some other subscriber at any other boardor in classifying the subscribers and so assigning them to the differentboards and connecting the wires from one board to another as to give those assigned to any given board the preference or first chance over all those assigned to succeeding boards.

In Figure l of the drawings I have shown a switch consisting of twoparts which I have designed for 'use upon the multiple switchboards. Cnc part, B', of the switch I term the line portion, and the other part, B, I terni the test portion.

Switches of this character designed for use upon telephone switch-boards are now generally called spring-jack switches,H or, briefly, jacks These switches have also been termed, specifically, jack-knife switches, and generally they have been termed bolts the term bolts being applied to any separate switch or line-terminal upon a switchboard, such separate line-terminals having been originally secured to the board by bolts `passing to the rear ot' the board, where connection is made with the lines.

The levers Zand l are normally held by the tension of the springs 7L and li', so as to close the contact-points o n and o n of each of the parts of a pair, A, of bolts or switches.

The frames k k are insulated from the contacts a a by means of the rubber bushing x fr.

The plug q is shown inserted so as to separate the contacts o Vn and open the test-circuit m. The reverse is shown in the right portion or bolt, B. The plug being re1ncvcd,the circuit oi' the telephone line which is perinanently connected with the frame or metallic piece c, will be closed to connection m.

The springs hand li of the double switch A or pair oi' bolts are insulated by hard rubber p p from t-he metallic parts or frames It: k', respectively.

In Fig.2 l have shown three multiple switch boards,which we will designate as the "tirst-,7 second,and third,"` respectively. One pair of bolts, Lis shown upon each of the duplicate boards. On the iirst board is shown an attendants telephone. V is the receiver; the plug; s s, the wires connecting with the local battery; r r and n2, the ground-wire. Each operator is thus provided with a similar telephone. Each subscriber has a pair of bolts upon each of the boards similar to those shown.

The subscriber/7s line c connects with one of g5 the bolts of the first board, as B', the right bolt, and through the contact-points by the line b with B the right bolt of A of the second board, and in the same way by line c with B of the third board; and now by line d connec- IOO tion is made between the right and left bolts B and B of the last board; and now by the line e to the left bolt, B, of the second board, and finally by the linef through the left bolt, B,of the iirst board, and by line g' to ground.

The iinal connection between any two subscribers is made by inserting a plug in each of their bolts B upon one of the boards, the plugs being connected by a conducting-cord. It is a law of this system that a plug inserted in any bolt B cuts off the subscribers line from all bolts B.

The operator at either of the boards wishing to connect with the wire of a called subscriber, does so by placing` a plug, t, in B of his pair of bolts A, and by throwing the battery to line he determines Whether the line is already in use at another board, and if it is, the calling subscriber is-told'tolwait and call again.

It will thus be seen that upon each board there is a pair of switches,A, or a spring-jack consisting of a line part and a test part provided for each line.

By applying a plug to the test portion of the double spring-jack of a line on either of the boards it may be determined whether or not the line is in use, the operator listening at his telephone or observing the bell in circuit with his telephone. Vhen pairs of bolts are thus used confusion is wholly obviated.

One bolt of each pair,as the left, B, may be entirely dispensed with, andv then each subscrber has a single bolt, B, upon each of the boards. In this case the bolts B are connected exactly as before with the subscribers line and with each other, the line d passing to ground,instead of connecting with the other bolt B of the pair, as shown in Fig. 3 of the drawings.

A' plug inserted in any bolt B cuts off the subscribcrs line from all the succeeding boards. Thus subscribers who are given the preference of the first board are undisturbed by having their lines crossed at'thc second, and those having the preference of the second board are interfered with only at the first. In this way confusion is partially obviatcd.

Prior to my invention two or more switchboards had been used at the central office of a telephone-exchange system, to each of which the same telephone-lines were connected.

Certain parts of my invention herein described are claimed in my application No. 26,902, ilcd February 24, 1881, for centralofiice circuits for telephoneexchanges. I

therefore limit my patent in this case to the combinations claimed. In a division of this case led September 22, 1884, I have claimed multiple switch-boards each provided with a single bolt for each subscriber, the bolts of each subscriber on the different boards being connected together and from the bolt on the last4 board with the ground, as illustrated in Fig. 3, Sheet 2, of this case.

I claim- 1. Thel combination of pairs of bolts A. for each subscriber upon each of the duplicate switch-boards, the several pairs belonging to a single subscriber being connected so that a plug inserted in any bolt B cuts off the subscribers line from all bolts B.

2. The combination of pairs of bolts, one pair on each duplicate boa-rd for each subscriber connected with the subscribers line, which passes successively to one bolt of each pair and in reverse order to the remaining bolt of each pair, and to ground, substantially as shown and described.

3. The combination and arrangement of bolts B and B reciprocally connected by springs l1, and 7i', and insulated by the hard rubber p and p', substantially as described and shown.

4. In a multiple switch-board system, the combina tion, with the different telephone-lines, of pairs of bolts or switches,one pair ofswitches on each board for each line, and one portion of each pair being for connection with the line and the other portion for testing, the telephone-lines being each connected through their diierent pairs of switches to ground, and a plug at each board whereby a test may be made by connection with the test portion of any pair, while the same plug may be used for insertion in the line portion of the same pair.

5. In a multiple switch-board system, the combination, with atelephone-line, of springjacks or pairs of bolts, one on each multiple board, each spring-jack or pair consisting of two parts, one portion forming aline part and the other portion a test part, and a groundcircuit provided with a terminal plug and including a battery and telephone-switching apparatus.

CHARLES E. SCRIBNER.

IOO 

